code: def gen_batch_of_features(cls, batch_of_audio):
      batch_size = batch_of_audio.shape[0]
      audio = batch_of_audio[0]
      feats = ddsp_metrics.compute_audio_features(
          audio, frame_rate=cls.frame_rate
      )
      for k, v in feats.items():
          feats[k] = np.tile(v[np.newaxis, :], [batch_size, 1])
      return feats
  
imports: from unittest import mock
  from absl.testing import parameterized
  import ddsp
  from ddsp.test_util import gen_np_batched_sinusoids
  from ddsp.test_util import gen_np_sinusoid
  import ddsp.training.metrics
  import numpy
  import tensorflow.compat.v2
label_desc: Use image node_id 3 for calling the MetricsObjectsTest obj's underlying member method code with example usage: obj.gen_batch_of_features(cls, batch_of_audio) and returns: feats